Need old school Chevy 454 help
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Topic: Need old school Chevy 454 help
Posted By: JimD
Subject: Need old school Chevy 454 help
Date Posted: 19 Sep 2019 at 9:43pm
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I was given a 1982 Motor home with Chevy 454. Runs amazing well, of course it only has 30K miles on it. Decided to take it on a long trip, so a test run was in order to the lake :) Changed oil and took off. Got stranded when the magnetic pickup went out. Then when home, the ignition module went. Then discovered the fuel pump leaking. Fixed all sorts of vacuum leaks, replaced wires, and plugs and then it started idling like poo. So i put a vacuum gauge on it tonight, and it's pulling 21"! But putting it in gear will kill it, and idle is nasty rough. I moved the gauge to the vacuum advance and tried it there, and suddenly the idle smoothed out, and I could it in gear. Apparently fixing all those vacuum leaks made the advance work, and when it works, it runs terrible! Going out tomorrow to time it with a light instead of by ear, but wanted to see if anyone had some insight? ------------- Owner of http://www.OKtractor.com" rel="nofollow - OKtractor.com PM for an instant response on parts. Open M-F 9-6 Central. We have new and used parts. 877-378-6543 |
Replies:
Posted By: desertjoe
Date Posted: 19 Sep 2019 at 10:07pm
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Well,,,I'll be rootin for you Jim..
 .I just cobbed onto a 454 engine myself. This the first big block chevy I've ever had and I'm anxious to fix whats needed and get it on the road,,,,can't wait,,, |
Posted By: shameless dude
Date Posted: 19 Sep 2019 at 10:36pm
| I have a 454 in one of my pickups, when cold it'll start on the 2nd or 3rd revalution, but if I shut it off, I have to crank and crank it to start. it runs well. I also have a 454 in one of my motorhomes. I had to replace a fan belt once and I see the previous owner had all the smog stuff removed or disconnected. it also ran real good when we traveled in it. this motorhome is an '89. I can't think of anything on yours except a good tune up and replace anything that is rubber. |
Posted By: Dakota Dave
Date Posted: 19 Sep 2019 at 10:37pm
| Retard the timing. Set it about 10 btdc with the vacuum disconnected and the hose plugged. Make sure your vacuum is connected to the time port on the carb and not manifold vacuum. Check and see if the anti diesel solenoid is connected and working. Did you follow the diagram exactly . I had an 83 that previous owners new better than GM and trashed all the pollution controls. Didn't run right till I corrected all the blocked off junk. I've got two 454s right now I really like the 95 fuel injected one. It's much better than the old carb on and only two vacuum lines on the hole thing. |
Posted By: desertjoe
Date Posted: 20 Sep 2019 at 2:15am
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Hey Shameless and Dakota Dave which type of distributor do your 454 engines use,,?? This one I got does not have a distributor, and I see 3 different types of ignition electronics on Ebay. HUMMmmm ,,,since I'ma gonna trash the 305 I wonder if the 305 distributor will work in the big block,,?? Anybody know,??
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Posted By: desertjoe
Date Posted: 20 Sep 2019 at 2:17am
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I know the starters are the same from the 305 to the 454 as I already used the 305 starter to run compression on the 454,,,,
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Posted By: Thad in AR.
Date Posted: 20 Sep 2019 at 4:37am
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Jim I don’t think it should have vacuum to the advance at idle??? Usually it goes to a port on the side of the carb that gives vacuum only at acceleration.. also curious of maybe the diaphragm in the advance cracked from age? |
Posted By: desertjoe
Date Posted: 20 Sep 2019 at 5:09am
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Yes,,Ten Four on the cracked diaphram,,,I have seen that before,,,as well as the vacuum advance rod stuck and not able to move advance system. I have seen this many times.
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Posted By: truckerfarmer
Date Posted: 20 Sep 2019 at 6:38am
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The internal components are the same, but a big block distributor has a longer housing and shaft. ------------- Looking at the past to see the future. '53 WD, '53 WD45, WD snap coupler field cultivator, #53 plow,'53 HD5B dozer Duct tape.... Can't fix stupidity. But will muffle the sound of it! |
Posted By: Dakota Dave
Date Posted: 20 Sep 2019 at 9:09am
| The carbureted engine has a standard GM HEI form some where around 76. the dually its in is a junk yard dog no two parts on it came from the same truck. the 95 has a EFI distributor. there are two different length housings for the big block. a truck engine should have the long one. new ones are so cheep its not worth messing with a housing pickup module cap rotor and coil cost about 4 x the price of a complete unit. for an 82 it should have a HEI. get the complete unit. they get corrosion in the housing under the module and the bushings get loose. a complete Accel performance one is only $85 from speedway motors. google is you friend when looking for auto parts. |
Posted By: desertjoe
Date Posted: 20 Sep 2019 at 10:26am
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Hey D Dave,,many thanks for thet info,,I was hopin to use the distributor (1982) from the 305,,it has the big old square lookin coil on top of the dsistributor,,,HEI isn't it,,?? I'ma gonna check out Amazon and ebay and go with a new one on this one,,,,,(gotta get back in ole Shameless's good graces,,,he keeps raising the price on my Chevy Allis,,,he does,,,,
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Posted By: JimD
Date Posted: 20 Sep 2019 at 9:08pm
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well.we.made.it about 200 miles. Fuel filter I think it bogging us. So if we disconnect the vacuum from the advance, it idles well,.but top end suffers Plug it in, and cant seem to retard enough to get an idle. I agree there shouldn't be vacuum at idle, but its beem.hooked that way a long time, but as I fixed back leaks it is now a problem. ------------- Owner of http://www.OKtractor.com" rel="nofollow - OKtractor.com PM for an instant response on parts. Open M-F 9-6 Central. We have new and used parts. 877-378-6543 |